The present invention relates generally to footwear and, more particularly, a new shock-absorbing sole, especially but not exclusively for sporting footwear.
In most sports activities, the lower limbs of participants are frequently subjected to systematic and continuous impact stresses deriving from contact between their feet and the ground. These stresses are particularly intense in those sports that are practiced on artificial or other hard surfaces such as track and field events, basketball and volleyball, as well as tennis, futsal, football, soccer and numerous other minor sports. The problems that can result therefrom are especially widespread in competitive practice. Indeed, the intensity and frequency of foot activity are such that the athlete must always seek to protect himself from traumatic events and overuse which may, in turn, cause injuries or, in any case, inflammatory phenomena.
The difficulties associated with impact stresses sustained by the lower limbs are similarly experienced in amateur practice. For this reason, amateur athletes will also seek to minimize the possibility of suffering an injury, and to obtain maximum comfort from the footwear employed.
Various systems for increasing the shock-absorbing properties of the sole are known, all based on the use of inserts of appropriate visco-elastic behavior. These inserts are arranged in the midsole, i.e. the layer between the outsole and the insole, at least in the zone where the stresses are greatest, which normally corresponds to the bearing point of the heel. One of the most widely used systems, for example, employs one or more capsules made of soft material and filled with air.
However, when shock-absorbing systems have to be designed and realized, it is not easy to optimize the shock-absorbing capacities without this being accompanied by negative effects as far as support for the plantar arch is concerned. Furthermore, account has also to be taken of other important factors, among them durability in time, limitation of production costs, integration with the transpiration system of the sole and, not least, the aesthetic aspects.
An object of the present invention is to provide a novel shock-absorption system for soles of footwear such as sporting footwear, that will be fully satisfactory from all of the aforementioned points of view and, as a result, will provide superior and long-lasting absorption of impact forces, maintain adequate support of the foot, and limit production costs, all without hindering transpiration and negatively affecting the aesthetic appearance of the footwear.
The shock-absorbing sole in accordance with the invention comprises a substantially flat, a midsole connected to said insole, and an assembly of shock-absorbing modules placed side by side within said midsole and running along a longitudinal direction of the sole, each module consisting of a wire-shaped element made of a high-strength and rigid material, the element being folded in such a way as to form a succession of upward-pointing loops lying in the plane that passes through the longitudinal axis of the module and is at right angles to the outsole, all the loops being inclined in the same direction. Each of these loops, in response to an impact of the sole to the ground, will bend with a compliance which is a function of the length of the loop, and will then tend to return quickly to its original position, substantially according to a damped aperiodic harmonic motion. The greater or lesser compliance of the assembly will also depend on the greater or lesser transversal density with which the modules are arranged in the midsole.